Hydraulic pump



Jan. 14, 1964 1-. F. BROLUND I 3,117,419

HYDRAULIC PUMP Filed April 6, 1961 2 Sheets-Sheet 1 3 was Theodav'e F ErohrncL A 41%, 1,40% MA -#95...

CBYTORIOBYJ Jan. 14, 1964 -r. F. BROLUND HYDRAULIC PUMP 2 Sheets-Sheet 2- Filed April 6, 1961 MVSMTOV Theodore. -d. 7 M M MM United States Patent 3,117,433 HYDRAULHC PUMP Theodore F. Eroiund, Rockford, 111., assignor to W. A. Whitney Mtg. o., Rocirtor iii, a corporation of Eii'n-eis Filed Apr. 6, 1961, Ser. No. 161,250 6 Claims. (Cl. 60-52) This invention relates to hydraulic pumps of the type including a rotary pumping element and having a control valve for alternately and selectively directing the output of the pump to diiierent members such as the opposite ends of a double-acting cylinder.

The primary object of the present invention is to provide in a pump of the above character a novel control valve which automatically changes the output of the pump as an incident to a reversal in the direction of rotation of the pumping element.

Another object is to provide a pump of the above character capable of developing high fluid pressures through two stages including a rotary, igh volume stage and a high pressure stage, and having a control valve operable to alternate the output of the high pressure stage between different places in response to reversal of the direction of rotation of the pumping element comprising the high volume stage.

A further object is to provide a novel seal to prevent leakage of pressure fluid between the pump casing and the valve plate While permitting relative angular movement therebetween to effect changes in the pump output.

The invention also resides in the novel construction and mounting of the pump casing which facilitates removal and replacement thereof in service use.

Other objects and advantages of the invention will become apparent from the following detailed description taken in connection with the accompanying drawings, in which FEGURE 1 is a fragmentary sectional view of a hydraulic pump unit embodying the novel features of the present invention, the section being taken in a plane through the axis of the pump and along the line 1 1 in FIG. 3.

FIG. 2 is an enlarged fragmentary sectional view taken along the line 2-2 in FIG. 1.

FIG. 3 is a fragmentary sectional view taken along the line 33 in FIG. 1.

FIG. 4 is an enlarged fragmentary section taken along the line 44- in FIG. 3.

PEG. 5 is a diagram of the hydraulic circuit in the novel pumping unit.

For purposes of illustration, the invention is shown in the drawings incorporated in a hydraulic pump unit It for furnishing fluid under pressure alternately to the opposite ends of a doubie-acting hydraulic cylinder 11 (FiG. 5) to slide a piston 12 back and forth therein and thereby to drive a machine tool such as a hydraulic press (not shown). The pumping unit is compactly assembled in a housing 13 to which a handle 1d may be attached to facilitate carrying and positioning of the unit in service use and a suitable power actuator, preferably a reversible electric motor 15, is mounted on one end of the housing with a drive shaft 17 extending into the housing and connected to a pump shaft 18 by means of a flexible coupling as. Suitable motor controls 21 may be built into the housing and connected to a power source (not shown) by an electric cord 22.

The pump shaft 18 projects into a casing 23 mounted in the housing and is journaled for rotation about a iixed axis in bearings 24 in the casing. Mounted in the casing is a two-stage pumping unit driven by the pump shaft and including a reversible rotary pump 25 for delivering a hi h volume of relatively low pressure fluid for rapid traverse of the piston 12 during the approach and return "ice strokes, and a second stage piston pump 27 for generating relatively high pressures during the work portion of the cycle.

In this instance, the first stage of the pump unit comprises a gear pump of well-known construction in which a driving spur gear 28 is mounted on the pump shaft and a meshing gear 30 is mounted on a. stub shaft 31 journaled in the casing 23 to rotate about an axis paralleling the pump shaft. When the pump shaft is driven 'by the motor 15, oil is drawn through a filtering screen 32 in a reservoir 33 formed in the base of the housing and is carried around the periphery of the gears to the output side of the pump. The second or high pressure stage 27 of the unit preferably is a pump of the axial plunger type including a plurality of axially disposed cylinders 3-4, three in this instance, mounted in the casing and communicating with the gear pump to receive low pressure fluid therefrom. Means is provided for converting the rotary motion of the pump shaft into linear motion of pistons 35 slidable in the cylinders 34; In this instance, this means comprises a swash plate 37 (FIG. 1) mounted adjacent the inner end of the shaft 18 and having a relieved end surface 38 inclined relative to the shaft axis, and a floating ring 4% maintained par ailel to the swash plate by an annular thrust bearing 41 between the plate and the ring. Pressure fluid pumped into the cylinders 34 by the gear pump urges the pistons against the ring and, during rotation of the shaft 18, the swash plate imparts a wobbling motion to the ring to emit the pistons back and forth in the cylinders.

As shown in FIG. 5, opposite sides of the gear pump communicate with the reservoir 33 through lines 42 and 43. Appropriate flow control valves 44 and 45 respectively in these lines open to permit oil to pass into the pump from either side but close to check flow back into the reservoir. Thus, if the driving gear 28 is rotated in a counter-clockwise direction as viewed in FIG. 5, the check valve 44 opens as fiuid is drawn through line 42 into the pump, and check valve 45 closes to prevent return flow through line 43 with a resulting flow, as indicated by the arrows in FIG. 5, into a line 47 opening into the cylinders 34. In the opposite direction of rotation of the gears, oil is sucked in through line 43 and again is discharged into line 47. Check valves 48 in lines 42 and 43 open to permit flow into line 47 while preventing flow back to the pump. Thus, the first stage pump feeds oil to the second stage in both directions of rotation.

During the approach and return strokes of the piston 12 when rapid traverse may be desired, the full capacity of the low pressure pump 25 flows through the piston pump '27 and into the cylinder 11. When the maximum low pressure is attained, however, an adjustable unloading valve 5% is opened to unload the full capacity of the gear pump into the reservoir, and check valves 51 in lines 52 leading to the cylinders 34 close to permit the high pressure pump to build up the pressure without back flow into the low pressure line 47. Consequently, high pressure oil is pumped by the pistons through an outlet port 53 communicating with the cylinders through lines 54. By means of a direction control valve, this flow may be directed from the outlet 53 selectively and alternately to opposite ends of the cylinder 11 to reciprocate the piston 12 therein.

The present invention contemplates a novel and improved directi'on-control valve which maybe operated to alternate the output of the pump unit 10 merely by reversing the direction of rotation of the rotary pump 25. For this purpose, the casing 23 is journaled in the housing to rotate freely about a fixed axis and the outlet port 53, which preferably is formed in the end 55 of the casing, is radially spaced from the casing axis. As a result, the reactive force of the rotary pump upon reversal of the irection of rotation of the pump shaft 18 causes the casing to turn in the housing and shift the outlet port through an arc corresponding to the turning of the casing. Coacting means on the casing and the housing limit turning of the casing between two predetermined positions, and two apertures 57 and 58 formed in the housing alternately register with the outlet port in the predetermined positions to receive pressure fluid from the high pressure pump.

Herein, the casing telescopes with and is journaled for rotation in the housing 13 in bushings 69 and 61 encircling the casing adjacent each end thereof. The bushing 66 is seated in the hole through which the motor shaft 17 projects and snugly receives a cylindrical neck 62 concentric with the casing and formed integrally with the end 63 thereof. The second bushing 61 is seated against the housing and telescopes snugly with a collar 64 encircling the casing. Suitable rings 65 around each bushing provide a fluid-tight seal preventing oil leakage from the housing. To position the casing axially while permitting it to turn freely in the housing, an annular thrust bearing 67 is mounted between the end of the casing and the adjacent wall of the housing. The wall of the housing adjacent the other end 55 of the casing comprises a retaining plate 68 which extends across the end of the casing and is secured to the housing as by bolts 70. This plate 68 bears against a boss 71 formed on the end of the casing around the outlet 53, thus axially positioning the casing against the thrust bearing 67.

In this instance, the means for limiting turning of the casing in the housing comprises a pin 72 projecting from the end of the casing and into a slot 73 formed in the plate 63 to permit limited arcuate movement of the pin as the casing turns in opposite directions, the opposite ends 74 and 75 or" the slot alternately abutting against the pin. Also formed in the plate 6% are the two apertures 57 and 58 for registering with the outlet port 53 in the alternate positions of the casing as determined by the pin and slot. Herein, the aperture 57 communicates with a conduit 77 for feeding pressure fluid to one end of the double-acting cylinder 11, and the other aperture 58 communicates with a conduit 78 leading to the other end of the cylinder. Consequently, when the pump shaft 18 is driven in a counter-clockwise direction as viewed in FIGS. 3 and 5, the pin is swung against the right end 74 of the slot and the outlet port registers with the aperture 57. Thus, oil is pumped into the upper end of the cylinder 11. When the direction of shaft rotation is reversed by reversing the electric motor, the casing turns in the housing and shifts the pin against the opposite end 75 of the slot where the port 53 is alined with the aperture 58. Then oil is pumped into the lower end of the cylinder 11.

Relief valves 80 may be mounted in the conduits 77 and 78 to control the maximum pressure generated on opposite sides of the piston. These valves may be of the spring-loaded plunger type adjustable to the desired pressure merely by turning a set screw 81 to increase or decrease the compression of the spring 82 and having an outlet 83 opening through the set screw and communieating with the reservoir. Check valves 84 interposed in the lines 54 between the cylinders 34 and the outlet port hold the line pressure to lock the piston 12 against movement when the pump is idling or inoperative.

Passages 85 and 86 for the return of exhaust fluid from the opposite ends of the cylinder to the reservoir may be formed in the casing with notches 87 and 88 in the end of the casing on each side of the outlet forming inlet ports communicating with the passages as shown in FIG. 4. With this arrangement, the notch 88 registers with the aperture 58 when the outlet port 53 is alined with the other aperture 57, and oil forced from the lower end of the cylinder as the piston moves downwardly fiows through the aperture 58 and back to the reservoir through the passage Similarly, as oil is pumped into the lower end of the cylinder tln'ough'the conduit 78, the exhaust '4 from the cylinder flow back to the reservoir through the aperture 57 and the notch 87.

To provide a fluid-tight seal between the relatively movable surfaces of the valve plate 68 and the boss 71 on the end of the casing, a sleeve 89 is inserted in the enlarged end 93 of the outlet port and urged into abutment with the valve plate by a coiled spring 91 compressed into the port. With the sleeve held against the plate by the spring 91 so that a flange 92 encircling the inner end of the sleeve is exposed to pressure fluid, a greater area of the sleeve is exposed to pressure fluid at the inner end than at the end adjacent the plate and the sleeve is pressed tightly against the plate 68 as the pressure builds up, thereby preventing oil leakage between the end of the sleeve and the plate. A suitable O ring 93 prevents leakage around the sleeve.

The open end of the housing may be covered by an end plate 94 secured to the housing as by a machine screw 95 threaded into the valve plate. With this arrangement, the entire pump unit may be removed quickly and easily as a cartridge for repair or replacement simply by removing the end plate 94 and the valve plate 68 and sliding the casing out of the bushings 6t) and 61. Thus, the maintenance on the pump conveniently may be performed on a Work bench and, if desired, a spare pump cartridge may be substituted to continue service use of the unit while repairs are being made.

I claim as my invention:

1. In a hydraulic pump, the combination of, a housing, a cylindrical casing journaled in said housing to rotate about a fixed axis, a reversible rotary pump including a pump element disposed within and journaled on said casing to turn about an axis paralleling the casing axis, a shat journaled in and concentric with said casing and oper to drive said pump element selectively in opposite di 6- tions, a plurality of cylinders mounted on said casing and communicating alternately with opposite sides of said rotary pump to receive pressure iluid from the output side of the pump in each direction of rotation of the latter, said casing being formed with an outlet port spaced radially from said casing axis and communicating with said cylinders, a plurality of pistons slidahly mounted in said cylinders, means for converting the rotary motion of said shaft into linear motion of said pistons relative to said cylinders to pump said fluid through said outlet port, the reactive force of said rotary pump upon reversal of the direction of rotation of said shaft causing the casing to turn in the housing, and means on said casing and said housing coacting to limit turning of said casing between two predetermined positions, said housing having two apertures disposed adjacent said outlet port and alternately communicating with said outlet port in said predetermined positions of said casing whereby reversal of the direction of rotation of said rotary pump shifts the output of cylinders from one aperture to the other.

2. In a hydraulic pump adapted to deliver pressure fluid alternately to opposite ends of a ram and reciprocate the latter back and forth, the combination of, a housing, a casing journaled in said housing to rotate about a fixed axis, a reversible rotary pump including a pump element disposed within and journaled on said casing to rotate about an axis paralleling said casing axis, a shaft rotatably mounted on said housing and operable to drive said rotary pump alternately in opposite directions, a source of pres sure fluid communicating with the intake side of said rotary pump in each direction of rotation of the latter, the

reactive force or" said rotary pump upon reversal of its 7 direction of rotation causing said casing to turn in said housing, a piston pump mounted in said casing and communicating with the output side of said rotary pump in each direction of rotation thereof to receive pressure fluid therefrom, said casing being formed with an outlet port spaced radially from said casing axis and communicating with said piston pump to receive pressure fluid therefrom, means on said casing and said housing coacting to limitturning of the casing between two predetermined positions, said housing having two apertures therein alternately communicating with said port as the casing turns back and forth between said positions and adapted to be connected to opposite ends of the ram whereby reversal of the direction of rotation of said rotary pump shifts the output of said piston pump back and forth between the opposite ends of the ram, and inlet ports in said casing spaced on opposite sides of said outlet port, one of said inlet ports comunicating with one of said apertures to receive exhaust fluid from one end of the ram when the outlet port is in communication with the other aperture and is delivering pressure fluid to the other end of the ram.

3. In a hydraulic pump, the combination of, a housing having an open end; a pump cartridge rotatably mounted in said housing and including a cylindrical casing telescoped into said housing through said open end and journaled in the housing to rotate about a fixed axis, a reversible rotary pump including a pump element journaled on said casing to turn about an axis paralleling said casing axis, and a piston pump mounted in said casing and having an inlet communicating alternately with opposite sides of said rotary pump to receive pressure fluid from the rotary pump in both directions of rotation of the latter; a drive shaft rotatably mounted on said housing and projecting into one end of said casing, said shaft being connected to said rotary pump to drive the latter alternately in opposite directions; means for converting the rotary motion of said shaft into linear motion of said piston pump; said casing being formed with an outlet port radially spaced from said casing axis and communicating with said piston pump to receive pressure fluid therefrom, the reactive force of said rotary pump upon reversal of its direction of rotation causing said cartridge to turn in said housing; said housing including a plate extending across said open end and engaging the adjacent end of said cartridge to position the latter axially in the housing; and means on said casing and said housing coacting to limit turning of the cartridge between two predetermined positions, said housing having two apertures therein adjacent said port and alternately communicating with the port as said cartridge turns back and forth between said predetermined positions whereby reversal of the direction of rotation of said rotary pump shifts the output of said piston pump from one aperture to the other, and said plate being removably secured to said housing whereby said cartridge may be removed therefrom as one unit and replaced by a similar unit.

4. In a hydraulic pump, the combination of, a housing, a casing journaled in said housing to rotate about a fixed axis, a reversible rotary pump including a pump element journaled on said casing to turn about an axis paralleling said casing axis, a drive shaft rotatably mounted in said casing and connected to said rotary pump to drive the latter alternately in opposite directions, a piston pump mounted on said casing and having an inlet communicating alternately with opposite sides of said rotary pump to receive pressure fluid from the rotary pump in both directions of rotation of the latter, means for converting the rotary motion of said shaft into linear motion of said piston pump, said casing being formed with an outlet port radially spaced from said casing axis and communicating with said piston pump to receive pressure ifluid therefrom, the reactive force of said rotary pump upon reversal of its direction of rotation causing said casing to turn in said housing, and means on said casing and said housing coacting to limit turning of the casing between two predetermined positions, said housing having two apertures therein adjacent said port and alternately communicating with the port as said casing turns back and forth between said positions whereby reversal of the direction of rotation of said rotary pump shifts the output of said piston pump from one aperture to the other.

5. In a hydraulic pump adapted to deliver pressure fluid alternately to opposite ends of a ram and reciprocate the latter back and forth, the combination of, a housing, a casing journaled in said housing to rotate about a fixed axis, a reversible rotary pump including a pump element journaled on said casing to rotate about an axis paralleling said casing axis, a shaft rotatably mounted on said housing and operable to drive said rotary pump alternately in opposite directions, a source of pressure fluid communicating with the intake side of said rotary pump in each direction of rotation thereof, the reactive force of said pump upon reversal of its direction of rotation causing said casing to turn in said housing, said casing being formed with an outlet port spaced radially from said casing axis and communicating with the output side of said rotary pump in each direction of rotation thereof, means on said casing and said housing coacting to limit turning of the casing between two predetermined positions, said housing having two aperuures therein alternately communicating with said port as the casing turns back and forth between said positions and adapted to be connected to opposite ends of the ram thereby to convert the reversing flow through said rotary pump into alternating flow to said opposite ends and reciprocate the ram, and inlet ports in said casing spaced on opposite sides of said outlet port, one of said inlet ports communicating with one of said apertures to receive exhaust fluid from one end of the ram when the outlet port is in communication with the other aperture and is delivering pressure fluid to the other end of the ram.

6. In a hydraulic pumping apparatus, the combination of, a housing, a casing journaled on said housing to rotate about a fixed axis, a reversible rotary pump including a pump element journaled in said casing to rotate about an axis paralleling said casing axis, means for driving said element selectively in opposite directions whereby the reactive force of said pump upon reversal of the rotation of said element causes said casing to turn about said axis, means on said casing and said housing coacting to limit such turning and hold said casing alternately in two predetermined angular positions, means for delivering pressure fluid to the intake side of said pump in both direc tions of rotation of said element, said casing being formed with an outlet port radially spaced from said axis, and means in said casing for delivering the output of said pump to said outlet port in each of said positions, said housing having two angularly spaced apertures therein alternately communicating with said outlet port in said two positions to receive the output of said pump therefrom whereby said pump output is alternated between said two apertures by reversing the direction of rotation of said element.

References Cited in the file of this patent UNITED STATES PATENTS 1,717,814 Strong June 18, 1929 1,893,125 Eiszantz Jan. 3, 1933 1,946,510 Truesdell Feb. 13, 1934 2,128,330 Schlitz Aug. 30, 1938 2,299,824 Kalin Oct. 27, 1942 2,414,187 Borsting Jan. 14, 1947 2,661,700 Towler et a1. Dec. 8, 1953 2,766,693 Wells Oct. '16, 1956 2,780,170 Stoyke et a1 Feb. 5, 1957 2,808,780 Hoekstra Oct. 8, 1957 FOREIGN PATENTS 516,790 Great Britain Jan. 11, 1940 646,310 Great Britain Nov. 22, 1950 828,115 Great Britain Feb. 17, 1960 954,077 France June 6,1949

OTHER REFERENCES Lynch, abstract of application Serial Number 68,614, pub. December 4, 1951, 653 O.G. 

1. IN A HYDRAULIC PUMP, THE COMBINATION OF, A HOUSING, CYLINDRICAL CASING JOURNALED IN SAID HOUSING TO ROTATE ABOUT A FIXED AXIS, A REVERSIBLE ROTARY PUMP INCLUDING A PUMP ELEMENT DISPOSED WITHIN AND JOURNALED ON SAID CASING TO TURN ABOUT AN AXIS PARALLELING THE CASING AXIS, A SHAFT JOURNALED IN AND CONCENTRIC WITH SAID CASING AND OPERABLE TO DRIVE SAID PUMP ELEMENT SELECTIVLEY IN OPPOSITE DIRECTIONS, A PLURALITY OF CYLINDERS MOUNTED ON SAID CASING AND COMMUNICATING ALTERNATELY WITH OPPOSITE SIDES OF SAID ROTARY PUMP TO RECEIVE PRESSURE FLUID FROM THE OUTPUT SIDE OF THE PUMP IN EACH DIRECTION OF ROTATION OF THE LATTER, SAID CASING BEING FORMED WITH AN OUTLET PORT SPACED RADIALLY FROM SAID CASING AXIS AND COMMUNICATING WITH SAID CYLINDERS, A PLURALITY OF PISTONS SLIDABLY MOUNTED IN SAID CYLINDERS, MEANS FOR CONVERTING THE ROTARY MOTION OF SAID SHAFT INTO LINEAR MOTION OF SAID PISTONS RELATIVE TO SAID CYLINDERS TO PUMP SAID FLUID THROUGH SAID OUTLET PORT, THE REACTIVE FORCE OF SAID ROTARY PUMP UPON REVERSAL OF THE DIRECTION OF ROTATION OF SAID SHAFT CAUSING THE CASING TO TURN IN THE HOUSING, AND MEANS ON SAID CASING AND SAID HOUSING COACTING TO LIMIT TURNING OF SAID CASING BETWEEN TWO PREDETERMINED POSITIONS, SAID HOUSING HAVING TWO APERTURES DISPOSED ADJACENT SAID OUTLET PORT AND ALTERNATELY COMMUNICATING WITH SAID OUTLET PORT IN SAID PREDETERMINED POSITIONS OF SAID CASING WHEREBY REVERSAL OF THE DIRECTION OF ROTATION OF SAID ROTARY PUMP SHIFTS THE OUTPUT OF SAID CYLINDERS FROM ONE APERTURE TO THE OTHER. 